U.S. Pat. No. 8,609,855 B2 describes the preparation of 4-amino-5-fluoro-3-halo-6-(substituted)picolinates from 4,5,6-trichloropicolinates by a series of steps involving fluorine exchange, amination, halogen exchange, halogenation and transition metal assisted coupling. The 4,5,6-trichloropicolinate starting materials are typically prepared by the chlorination of 5,6-dichloropyridine-2-carboxylate-N-oxide; see, for example, Example 3 in U.S. Pat. No. 6,784,137 B2. It would be desirable to conveniently prepare the 4,5,6-trichloropicolinate starting materials from a more readily available source.